[Eva] add warning key unknown-size

src/plugins/e-acsl/tests/bts/oracle/bts2406.res.oracle

src/plugins/value/domains/cvalue/cvalue_init.ml

src/plugins/value/engine/initialization.ml

src/plugins/value/value_parameters.ml

src/plugins/value/value_parameters.mli

tests/builtins/oracle/imprecise.res.oracle

tests/misc/oracle/audit-out.json

tests/value/oracle/abstract_struct_1.res.oracle

tests/value/oracle/array_zero_length.0.res.oracle

tests/value/oracle/array_zero_length.1.res.oracle

tests/value/oracle/empty_union.res.oracle

tests/value/oracle/extern.res.oracle

tests/value/oracle/library.res.oracle

tests/value/oracle/not_ct_array_arg.res.oracle

tests/value/oracle/unknown_sizeof.0.res.oracle

tests/value/oracle/unknown_sizeof.1.res.oracle